[Distribution of the incidence of SGPT activity in blood donors]

Predonation SGPT (ALT) testing was performed in 5,706 blood donors (3,944 male, 1,762 female) with the Reflotron system. The values of SGPT activities (IU/l; 25 degrees C) are not normally distributed, whereas the log10 SGPT distribution is largely Gaussian (the arithmetic mean log10 +/- SD for female donors is 0.98 +/- 0.14 and for male donors 1.08 +/- 0.16, the antilog of the mean log10 9.5 and 12.1 IU/l, respectively). In the following the impact of SGPT testing at various exclusion levels on the percentage of deferred donors is shown: (1) female: cutoff level > 18.0 IU/l (mean log10 +2.0 SD) 2.8%, > 19.5 IU/l (+2.25 SD) 2.1%, > 21.1 IU/l (+2.5 SD) 1.8% and > 24.8 IU/l (+3.0 SD) 1.2% deferment. (2) male: cutoff level > 25.2 IU/l (mean log10 +2.0 SD) 2.7%, > 27.6 IU/l (+2.25 SD) 2.3%, > 30.3 IU/l (+2.5 SD) 1.4% and > 36.4 IU/l (+3.0 SD) 0.8% deferment. Using the current cutoff value of > 45 IU/l (according to German regulations, 1987) only 0.2% female (with SGPT > mean log10 +4.5 SD) and 0.3% male (with SGPT > mean log10 +3.5 SD) donors would be excluded. These findings demonstrate that different SGPT exclusion levels for men and women are necessary and that the current cutoff value of > 45 IU/l does not exclude donors who should better be rejected.